The objective of this study was to measure colonic mucosal and cytobrush sample messenger (m)RNA expression of interleukin (IL)-1β, IL-2, IL-12p40, IL-23p19, tumor necrosis factor-alpha (TNF-α) and chemokine C‐C motif ligand (CCL28) in dogs with IBD and healthy controls using quantitative real-time polymerase chain reaction (PCR), and assess their correlation with clinical disease activity, endoscopic and histopathologic score. The gene discussed is IL1B; the disease is inflammatory bowel disease.